Microbial Transformations of Selenite by Methane-Oxidizing Bacteria

Methane oxidizing bacteria are well known for their role in the global methane cycle and their potential for microbial transformation of wide range of hydrocarbon and chlorinated hydrocarbon pollution. In recent years it has also emerged that methane-oxidizing bacteria interact with inorganic pollutants in the environment, including heavy metals. Here we report what we believe to be the first study of the interaction of methane-oxidizing bacteria with selenite. Results indicate that the commonly used laboratory model strains of methane oxidizing bacteria, Methylococcus capsulatus (Bath) and Methylosinus trichosporium OB3b are both able to reduce the toxic selenite (SeO32-) form to nanoparticulate elemental selenium (Se0). Subsequently, volatile selenium-containing species were detected from the Mc. capulatus and Ms. trichosporium cultures, concomitant with the loss of red colour due to Se0 from both cultures. This suggests that both strains may have an additional activity that can either transform Se0 or selenite into volatile methylated forms of selenium. Collectively these results are promising for the use of methane-oxidising bacteria for bioremediation or suggest possible uses in the production of selenium nanoparticles for biotechnology.